München 2009 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 87: Gamma-Astronomie 6

T 87.2: Vortrag

Freitag, 13. März 2009, 14:15–14:30, M105

H.E.S.S. Observations of AGN — •M. Raue — Max-Planck-Institut für Kernphysik, Heidelberg, Germany

The mechanism and production site of very high energy (VHE; E > 100 GeV) gamma-ray emission in active galactic nuclei (AGN) is still a highly debated subject. While the number of source grew steadily over the past years (∼25 sources today) and rich multi-wavelength data-sets are available, almost all of the AGNs with VHE gamma-ray emission belong to the source class of blazars. For Blazars, the jet axis is closely aligned to the line of sight to the observer and the emission is likely relativistic boosted. Radio galaxies, on the other hand, have a resolved jet and can therefore provide unique insides in the physics of relativistic plasma jets. Up to now, M 87 is the only firmly established VHE gamma-ray emitting radio galaxy. M 87 showed fast (∼days) outbursts in the VHE regime in 2005 and 2008, which lead to strong constraints on the size of the emission region. Flux variations with even shorter time-scales in the order of minutes have been detected from the blazars PKS 2155-304 and Mkn 501 during flaring states. Recent results from H.E.S.S. observations of AGNs will be presented and the implications of the results discussed.